Using a check value serves to ensure data integrity during data transmission or storage, with a value, in the simplest case a checksum, being determined, for example calculated, from data in a telegram by means of a suitable method. The resulting value is then co-stored or, as the case may be, co-transmitted as a check value. The telegram recipient can likewise determine a check value from the data and compare said value with the sender's co-transmitted check value. If the two check values are different an error, in particular a transmission error, will have occurred. If the two check values are identical it is highly probable that the message will have been transmitted correctly.